Foam Purchasing: Do Your Homework

So, it is time to purchase a foam concentrate for the first time or replenish your current foam concentrate supply. What do you need to do now?

There are several considerations before you rush out to purchase those heavy buckets of bubble-making concentrate. The most important thing to remember, regardless of whether this is your initial purchase or you are replenishing your inventory, is to not let money be the sole deciding factor in your decision-making process. Many departments simply let the per-gallon cost of foam concentrate drive their decision on what to purchase. This can have disastrous consequences that will end up costing you a lot more than the savings you realized from buying a cheaper concentrate.

What Type?

The first decision in making a foam concentrate purchase is to determine what type of foam concentrate will be needed to properly protect your community. There are several options available on the market today, so determining the hazards to be protected is very important. If you live in a rural community with few or no Class B hazards, then you shouldn’t focus on purchasing Class B foam concentrate. On the contrary, if you have a large amount of Class B fuel storage in your community, you shouldn’t focus on Class A foam. If you have a mix of Class A and Class B fuels, then examining a proven National Fire Protection Association (NFPA) 18, Standard on Wetting Agents, compliant concentrate might be your best choice. You should spend time reading NFPA 18; NFPA 1150, Standard on Foam Chemicals for Fires in Class A Fuels; and NFPA 11, Standard for Low-, Medium-, and High-Expansion Foam. These three standards will provide you with the information you need regarding the types of foam concentrates available on the market and the fires they will properly work to extinguish. It is very important to do your research in determining what type of foam concentrate will best suit your community. You don’t want to invest a large amount of your community’s money in a concentrate that will not suit your needs.

If you determine an NFPA 18-compliant foam concentrate is best for you, then you have a little extra homework. You should request that the manufacturer provide you with a copy of its latest independent testing data showing the results for tests outlined in NFPA 18. The majority of NFPA 18 foam concentrates have been tested by Underwriters Laboratories to determine if they meets or exceed the testing outlined in NFPA 18. The manufacturer can provide you with a copy of its test data so you, the end user, can use performance data to compare the performance of the different NFPA 18-compliant foam concentrates. If you compare this test data, you will be able to determine which concentrates are the better performing concentrates. This research will greatly assist you in determining the best performing concentrates available to your department. If the manufacturer refuses to release its independent testing data, that should be a red flag regarding the concentrate’s performance abilities.


Your foam concentrate’s compatibility with other concentrates is an important factor in the purchasing process. If you are purchasing a foam concentrate for the first time, then concentrate compatibility is not going to be as big of a concern. If you are replenishing your current inventory, it is vital that whatever new foam concentrate you purchase be compatible with the foam concentrate already in your department—especially if the concentrate is going to be placed in a tank using an onboard delivery system. If you decide to take the low-bid approach and switch to foam concentrates that aren’t compatible and then mix them in an onboard storage tank, you could create a tank full of jellied foam snot. It does not take a large amount of incompatible foam concentrate to ruin the entire tank of concentrate. If two foam concentrates are mixed in an onboard foam tank, they will often plug the foam system and require draining the concentrate tank and flushing the entire foam system. I assure you, mixing incompatible foam concentrates will create much more work than taking your time to conduct research prior to your purchase.

Only consider mixing concentrates that are approved by both manufacturers as being compatible with each other. Even if the manufacturers state the concentrates are compatible, I recommend testing them yourself: Mix a small amount of the two concentrates in a jar to see how they react with each other. It is better to determine your concentrates aren’t compatible in a jar than to pour them together in your tank and ruin a large amount of foam concentrate.

Foam Creation

Prior to making any foam concentrate purchase, you need to determine if the concentrate you purchase is compatible with the method you will use to generate your foam solution. If you are using an inline foam eductor, you will face fewer delivery system compatibility issues than if you are using an onboard foam delivery system. If you are using an onboard foam delivery system, it is vital to determine if the system can deliver your foam concentrate to the foam manifold.

All fluids have viscosity, which is its resistance to flow. This is very important with foam concentrates, as viscosity can vary greatly from concentrate type to concentrate type. Viscosity is measured in centipoise, and all foam delivery systems have a maximum centipoise they can deliver. You should research your delivery system and determine the maximum centipoise it can deliver. Once you determine the maximum centipoise of the delivery system, it is very important that you research your foam concentrate and determine its centipoise. While researching the foam concentrate, be sure to pay attention to the temperature at which the foam concentrate’s centipoise was measured. All liquids increase in centipoise as their temperature is reduced. If you live in a cold climate, this can be very important. There are many foam concentrate manufacturers that only report the centipoise of their concentrate in the 70°F range. If you live in an area that experiences severe cold in the winter, the concentrate’s centipoise may be much higher than what is reported by the manufacturer. The higher centipoise may exceed the ability of the delivery system to properly function and deliver the proper foam stream. If you expect your foam delivery system to work properly, you must ensure your foam concentrate doesn’t exceed the maximum centipoise of the delivery system.

If you are using an onboard foam delivery system, it is important to be sure the delivery system can deliver the proper percentage of foam concentrate for the type of concentrate selected. There are many induction systems that cannot provide the lower concentrate percentages for many NFPA 18-compliant concentrates. If possible, you don’t want to deliver higher percentages than recommended by the manufacturer, as you are often simply wasting concentrate, which means you are wasting money. There are many injection foam systems that can deliver low percentages of concentrates but not higher percentages. You don’t want to purchase a three percent foam concentrate and have an onboard foam delivery system that can’t deliver foam concentrate at higher than a one percent solution. Prior to purchasing your concentrate, ensure your delivery system will deliver the concentrate you purchase.


Pricing is an important component to consider when making a foam concentrate purchase, although it shouldn’t be the sole determining factor for what is purchased. When examining the price of your foam concentrate, make sure you only look at the cost for your finished foam. If you only look at the price of your concentrate, you could possibly be spending more for a lower priced concentrate to generate the same amount of finished foam. Let’s look an example where a higher priced concentrate would be the better buy for your department.

If Concentrate A costs $30 a gallon and is used at 0.50 percent for Class B fires, and Concentrate B costs $20 a gallon and is used at one percent for Class B fires, which is the better deal? You might think a concentrate selling for $10 less per gallon would be, but the concentrate that costs more is the better deal.

To determine the actual finished foam cost, you need to determine how many gallons of finished foam each gallon generates. We will use simple math to determine how much foam concentrate is used and the total cost to generate 1,000 gallons of finished foam.

If you are using Concentrate A, you would need five gallons of concentrate to make 1,000 gallons of 0.50 percent Class B finished foam. The five gallons of finished foam is going to cost you $150, since the concentrate is $30 per gallon. To make the same 1,000 gallons of finished foam with Concentrate B, you are going to need 10 gallons of foam concentrate. The 10 gallons is required because Concentrate B requires one percent concentrate to extinguish the fire. The 10 gallons of Concentrate B will cost you $200.

The cost of Concentrate B is $10 a gallon cheaper, yet the total cost to generate the correct percentage of finished foam is $50 more than Concentrate A. This example demonstrates the importance of looking at the concentrate percentage and cost to generate finished foam rather than simply looking at the concentrate price per gallon.


You should consider the percentage of concentrate per gallon recommended by the manufacturer in your purchasing decision-making process. If you use a foam concentrate for Class B fires at 0.50 percent, and your onboard foam tank is 40 gallons, your apparatus will be able to generate 8,000 gallons of finished foam without requiring additional concentrate. If you purchase a foam concentrate that requires a three percent solution for Class B fires, that same 40-gallon foam tank is only going to generate 1,333 gallons of finished foam. As you can see, the ability to deliver your concentrate at a lower percentage is going to allow your onboard foam tank to generate significantly more finished foam using the same amount of concentrate. This can prove to be very beneficial when you have a large fire and you have multiple apparatus on scene that can generate large volumes of finished foam.

As you can see, there are many factors to consider when making a foam concentrate purchase. Do not rely on the salesperson to guide your decision-making process. Take the necessary time to conduct research and determine which concentrate is the best purchase for your community. The Internet is a wonderful resource for information on foam concentrates. Please take the time to do your homework so when you invest your community’s money in foam concentrate, you are making the best possible investment. A little extra time prior to the purchase will save you a considerable amount of time and money after the purchase. The time investment will also make your firefighters safer because they will be using the best possible foam concentrate to extinguish their fires.

SHAWN A. OKE is a 29-year veteran and chief of the Albemarle (NC) Fire Department. He has a bachelor’s degree in fire engineering technology from the University of North Carolina Charlotte. He is a graduate of the National Fire Academy Executive Fire Officer Program. Oke currently serves as an at-large member of the IAFC Safety, Health, and Survival Section board of directors. He is the cofounder of the Kill the Flashover project where he has been involved in extensive wetting agent research.

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